In general, a DC/DC converter is an electronic circuit that accepts a DC input (i.e., a power signal) at one voltage level and converts it to a DC output at a lower or higher voltage level. Such a converter is well-suited for circuit boards containing operating circuitry which requires a DC signal having a particular voltage level but that only has access to a different DC signal having a different voltage level. For example, one conventional processor requires both a 3.3 Volt DC signal and a 2.5 Volt DC signal for proper operation. If a processor circuit board manufacturer only has access to a 12 Volt DC signal, the manufacturer can manufacture a processor circuit board having the conventional processor and a set of converters which provides the 3.3 and 2.5 Volt DC signals to the processor in response to the 12 Volt DC signal thus enabling the processor to operate properly.
Some processors require multiple voltages in a particular startup sequence. For example, the above-described conventional processor requires a soft start 3.3 Volt DC signal and a soft start 2.5 Volt DC signal. In accordance with the startup sequence, the 3.3 Volt DC signal and the 2.5 Volt DC signal may never vary from each other by more than 1.2 Volts, and the 2.5 Volt DC signal may never exceed the 3.3 Volt DC signal by more than 0.4 Volts. For such a processor, the circuit board manufacturer typically custom designs external control logic and installs the external control logic between the outputs of the converters (i.e., metal contacts) and the processor. The control logic typically resides on a section of circuit board space that is approximately 2 inches by 2 inches between the converters and the processor, and is configured to electrically isolate the processor from the converter outputs in the event the converters improperly provide the power signals. Accordingly, if the converters provides the power signals out of the particular startup sequence (e.g., if the 3.3 Volt DC signal varies from the 2.5 Volt DC signal by more than 1.2 Volts), the control logic disconnects the processor from the converter outputs to avoid damaging the processor.
Some converters have other special features. For example, one conventional converter includes (i) a sensing contact and (ii) a feedback circuit connected to the sensing contact. A circuit board manufacturer typically connects one end of an external Schottky diode to the converter output, and the other end of the external Schottky diode to the sensing contact. If the output voltage sensed at the sensing contact (i.e., sensed across the Schottky diode) is too high, the feedback circuit directs the converter to provide less current to lower the output voltage. If the output voltage is too low, the feedback circuit directs the converter to provide more current to increase the output voltage.
In some high current demand situations, circuit board manufacturers may install multiple converters that provide the same output voltage. For example, a particular converter may not be able to provide enough current to meet the demands of a particular processor. In such a situation, the manufacturer can install two converters having the above-described feedback capabilities onto a processor circuit board to accommodate the high current demands of the processor. The two converters provide the same output voltage and enough current to satisfy the high current needs of the processor. During periods of operation that requires less current, the feedback circuits of the two converters will sense an increase in the output voltage provided by the converters and direct the converters to provide less current.
As another example of a converter with a special feature, some converters include overvoltage protection circuits. One conventional converter includes (i) a switched-capacitor circuit that provides an output voltage, (ii) a converter output (e.g., a metallic contact) for connecting to external operating circuitry (e.g., a processor), and (iii) an overvoltage protection circuit interconnected between the switched-capacitor circuit and the converter output. The overvoltage protection circuit is configured to disconnect the switched-capacitor circuit from the converter output if the output voltage exceeds a predetermined threshold. Accordingly, when the output voltage of the power signal is excessive, the overvoltage protection circuit prevents the power signal from reaching and possibly damaging the external operating circuitry.
As yet another example, some converters include trim pins which, when soldered to a resistor or a voltage divider that provides a particular voltage, causes the converter to provide an output voltage that is based on the particular voltage. For example, suppose that a circuit board manufacturer (i) requires a 3.0 Volt DC signal and (ii) has both expensive 3.0 Volt converters and less expensive 3.3 Volt converters available. The manufacturer may be able to use the less expensive 3.3 Volt converters by utilizing the trim pin feature of the 3.3 Volt converters. To this end, the manufacturer can solder the trim pin of each 3.3 Volt converter to a resistor providing an appropriate voltage that directs the 3.3 Volt converter to provide the 3.0 Volt DC signal rather than a 3.3 Volt DC signal thus enabling the manufacturer to take advantage of the lower cost 3.3 Volt converters.
Unfortunately, there are deficiencies to the above-described conventional converter configurations. For example, in the earlier-described conventional converter configurations in which a processor circuit board manufacturer custom designs an external control logic circuit that disconnects the converters from the processor if the converters provide a set of power signals out of a required startup sequence, the manufacturer is burdened with the task of designing a new external control logic circuit for each new combination of converters. That is, the manufacturer requires a first external control logic circuit for a circuit board that uses a 5.0 Volt converter and a 3.3 Volt converter to provide a particular startup sequence, a second external control logic circuit for a circuit board that uses a 3.3 Volt converter and a 2.5 Volt converter to provide a particular startup sequence, and so on. Additionally, each external control logic circuit requires circuit board space (e.g., a 2 inch by 2 inch area), a valuable resource which could otherwise be used for other circuitry. Furthermore, although the external control logic electrically isolates the processor from the converters to avoid damaging the processor, the converters remain in operation thus providing an unsafe situation (e.g., the possibility that the converters or the power supplies could damage themselves, the circuit board, the power supply feeding the converters, etc.).
Additionally, in the earlier-described conventional configurations in which a processor circuit board manufacturer installs multiple converters that provide the same output voltage in high current demand situations, there is no control over how much current each converter provides. Accordingly, for a circuit board that uses two converters to provide the same output voltage to a processor, one converter often provides a large amount of current (e.g., 10 amps or 99% of the current) while the other converter provides substantially less current (e.g., only 100 milliamps or 1% of the current). As such, if the converter that provides the larger amount of current fails, the other converter which provided substantially less current is now forced to immediately provide a significant amount of current which can damage that converter as well as the circuitry connected to that converter (e.g., the converter providing 100 milliamps or 1% of the current may be required to immediately provide more than 10 amps or 100% of the current).
Furthermore, in the earlier-described conventional configurations in which a conventional converter includes an overvoltage protection circuit that disconnects the switched-capacitor circuit from the converter output in response to an overvoltage condition, the switched-capacitor circuit can remain connected to the input feed. Accordingly, in some situations, the switched-capacitor circuit can overcharge beyond its designated voltage to the value of the input voltage, and thus provide an unsafe situation (e.g., that damages the converter components, the circuit board, the power supply feeding the converter, etc.).
Also, in the earlier-described conventional configurations in which a conventional converter includes a trim pin soldered to a resistor or voltage divider to enable the converter to provide an adjusted constant output (e.g., to enable a 3.3 Volt converter to provide a 3.0 Volt DC signal), the configuration does not lend itself well to adjustment. In particular, the configuration does not allow for raising or lowering the output voltage for stress testing. For example, on a circuit board that includes the converter and operating circuitry, there is little or no opportunity to direct the converter to increase the output voltage by 10% or decrease the output voltage by 10% to stress test the circuit board since the trim pin of the converter is soldered to a resistor or a voltage divider.
In contrast to the above-described conventional configurations, embodiments of the invention are directed to techniques for providing a set of power signals to operating circuitry mounted on a circuit board that overcome many or all of the above-described deficiencies.
One embodiment of the invention is directed to a circuit board that includes a section of circuit board material and operating circuitry mounted to the section of circuit board material. The operating circuitry is configured to receive a set of soft start power signals in a particular sequence when transitioning from a startup state to a normal operating state. The circuit board further includes a converter system having a first circuit, a second circuit and an interconnection mechanism. The first circuit includes a first converter that provides a first soft start power signal to the operating circuitry, and a first controller that provides a first control signal indicating whether the first converter properly provides the first soft start power signal. The second circuit includes a second converter that provides a second soft start power signal to the operating circuitry, and a second controller that provides a second control signal indicating whether the second converter properly provides the second soft start power signal. The interconnection mechanism electrically connects the first controller of the first circuit with the second controller of the second circuit. The first controller disables the first converter when the second control signal indicates that the second converter improperly provides the second soft start power signal. Similarly, the second controller disables the second converter when the first control signal indicates that the first converter improperly provides the first soft start power signal. Accordingly, the controllers can disable the converters in the event of improperly providing the power signals. Additionally, when the converters are packaged with the controllers as single devices, no custom-designed external control logic is required to disconnect the operating circuitry from the converters since the internal controllers disable the converters thus saving time and effort that would otherwise be required to design and customize the control logic and thus saving circuit board space that would otherwise be occupied by the external control logic. Furthermore, disabling the converters is safer than the conventional approach of simply disconnecting the operating circuitry from conventional converters which can continue to operate.
In one arrangement, the first controller further provides a first current indication signal which is proportional to a value of current of the first soft start power signal, and the second controller further provides a second current indication signal which is proportional to a value of current of the second soft start power signal. The first controller directs the first converter to provide the first soft start power signal based on the second current indication signal provided by the second controller. Similarly, the second controller directs the second converter to provide the second soft start power signal based on the first current indication signal provided by the first controller. For example, each controller can direct a corresponding converter to provide roughly 50% of the current based on the first and second current indication signals, (e.g., sensing through power MOSFETs). Accordingly, if a converter fails, the remaining converter can compensate by providing 100% of the current rather than roughly 50% of the current. The transition from providing 50% of the current to 100% of the current is less extreme and thus less likely to damage the converter any related circuitry. This is a safer operation than requiring a converter to immediately transition from providing approximately 1% of the current to 100% of the current as in the earlier-described conventional converter configuration.
In one arrangement, the each converter includes (i) switched-capacitor circuitry that electrically connects with a voltage reference and a ground reference in an alternating manner to provide a soft start power signal to the operating circuitry, (ii) an overvoltage protection switch interconnected between the switched capacitor circuitry and the voltage reference, and (iii) a control circuit coupled to the switched capacitor circuitry and the overvoltage protection switch. The soft start power signal has an output voltage value that is between a voltage reference value of the voltage reference and a ground reference value of the ground reference. The control circuit is configured to open the overvoltage protection switch when the output voltage value exceeds a predetermined threshold. Accordingly, the overvoltage protection switch cuts off the switched-capacitor circuitry from the voltage reference in response to an overvoltage condition thus preventing the switched-capacitor circuitry from inadvertently overcharging and otherwise causing damage.
In one arrangement, the first circuit further includes a control register. In this arrangement, the first controller selectively directs the first converter to provide (i) the first soft power signal with a regulated voltage value regardless of a value of an input power signal when the control register stores a first control value, and (ii) the first soft start power signal with a margined voltage value based on the value of the input power signal when the control register stores a second control value that is different than the first control value. Accordingly, the first circuit can be programmed to operate in a normal operating mode (i.e., to provide a regulated power signal) or a test mode (i.e., to provide a margined voltage value) for stress testing the circuit board under extreme power signal conditions.
The features of the invention, as described above, may be employed in computer systems, devices and methods as well as other computer-related components such as those of EMC Corporation of Hopkinton, Mass.